Facebook is yet to comment on the branding, although a filing in the USPTO database – spotted by TechCrunch – shows that FiftyThree has now applied to trademark the term ‘Paper’, putting further pressure on the social network.

The bid was submitted on January 30, the day that Facebook first announced Paper. The startup has already trademarked ‘Paper by FiftyThree‘, although the inclusion of its company name arguably gives Facebook some leverage for using the word ‘Paper’ on its own.

Facebook Paper went live in the US App Store yesterday, causing FiftyThree CEO and co-founder Georg Petschnigg to publicize his discontent online. In short, he’s worried that Facebook’s new app will cause confusion amongst new and existing users and damage the brand that it’s been building since 2012.

Although Facebook is said to have apologized to FiftyThree for using the app, it hasn’t offered to change the name or take further action to rectify the problem. “An earnest apology should come with a remedy,” Petschnigg said.

Nick Summers is a technology journalist for The Next Web. He writes on all sorts of topics, although he has a passion for gadgets, apps and video games in particular. You can reach him on Twitter, circle him on Google+ and connect with him on LinkedIn.